<template>
  <div class="container">
    <div class="item1"></div>
    <div class="item2"></div>
    <div class="item3"></div>
  </div>
</template>
<script>
export default {
  data() {
    return {};
  },
  methods: {},
};
</script>
<style scoped>
.container {
  display: flex;
  flex-direction: row;
  height: 100%;
  background: #ccc;
  /* 水平居中 */
  justify-content: center;
  /* 垂直居中 */
  align-items: center;
}
.item1 {
  height: 100px;
  width: 100px;
  background: red;
}
.item2 {
  height: 200px;
  width: 200px;
  background: blue;
}
.item3 {
  height: 300px;
  width: 300px;
  background: green;
}
</style>